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Originally posted by resqcapt19:
DS
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I simply assume that I need two ground rods for my primary (permanent) electrode system.
Even if you use the water pipe 2 ground rods are requires unless you can prove that a single rod complies with the 25 ohm rule in 250-56

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I don't count it as a primary electrode for a number of reasons.
At this time the code does. There are a number of reasons not to use the metal underground water piping system as a grounding electrode, but CMP5 has not yet agreed with those reasons.

The comments by Mr.Schiff about not using the metal underground piping as an electrode to improve safety of water department workers are not correct. If we stopped using it as the grounding electrode, but still bonded it to the grounding system inside the building the same safety problem will exist. The only way to improve safety for the water department workers would be to use a dielectric fitting in the water service to isolate the interior and exterior parts of the metal piping system. This is often done by gas utilities that are still using metal pipe for exterior gas supply lines.
Don(resqcapt19)

That argument by water departments IMO is unfounded, here is why, the main purpose of the grounding electode system is to shunt to ground strikes by lightning, line surges via a suspect line transformer, that 25 ohms to ground is not going to trip a breaker or blow a fuse, that said, by bonding the interior water system to the neutral bar in the service will trip a breaker if it comes in contact with a hot conductor. Lestwise thats how usin's in Ohio do it.